The present invention relates generally to a part fixture for a laser drilling operation. More specifically, the present invention is directed to a fixture for turbine nozzles that does not interfere with a laser drilling operation on the turbine nozzle.
In general manufacturing of turbine nozzles and other parts, the fixtures used for manufacturing the parts have fixed locators to position the part in the proper orientation for machining. The fixed locators are usually positioned against the part""s datums. The datums of the part are preset locations or points on the part that, when support is applied to those locations, prevent the part from translating along the three axes of a three axis orthogonal coordinate system (e.g. x, y, and z axes) and prevent the part from rotating about each of the three axes. Generally, a three-dimensional object will require 6 datum points. Using the datums of a part positions the part into a known position, which can then be used for a subsequent machining operation or for an assembly operation.
Generally, the vanes of a turbine nozzle have 4 of their 6 datum points located on the leading edge of the vane. FIGS. 1 and 2 illustrate a vane 100 of a turbine nozzle and the corresponding datum points 102-112 for the vane 100. As can be seen from FIGS. 1 and 2, datum points 102-108 are located on the leading edge of the vane 100. During the manufacturing of a vane for a turbine nozzle, it is necessary to laser drill cooling holes into the leading edge of the vane. To be able to laser drill cooling holes into the leading edge of a vane, the vane is generally positioned into a fixture and clamped at its datum points, as discussed above. However, the clamping of the part at its datum points by the fixture can interfere with the laser drilling operation, if holes are to be laser drilled at or in the vicinity of the datum points.
FIGS. 3 and 4 illustrate a prior art fixture 300 used for laser drilling holes in a vane 100. The vane 100 is placed into a base 302 and a plate 304 is attached to the base 302 to hold the vane 100 in the fixture 300. The plate 304 has 4 fixed datum locators 306 that are used in positioning the vane 100 and locating the leading edge of the vane 100. The fixture 300 utilizes several screws 308 to hold the part or vane 100 against the leading edge locators 306. These screws 308 are a form of an adjustable work support. Once the part 100 is secured against the locators 306, screw clamps 310 are used to hold the part 100 against the screws or work supports 308 of the fixture 300. The clamps 310 are used to ensure that there is not any translation or rotation of the part 100. An iterative process of adjusting the work supports 308 and the clamps 310 is used to ensure that the vane 100 is seated against the locators 306. Once the part 100 is properly located and clamped, the plate 304 containing the leading edge locators 306 is removed permitting laser access to the leading edge of the vane 100. This process of iterative adjustment of the screws 308 and clamps 310 to position the vane 100 is time consuming, prone to part miss-load and ergonomically unfriendly.
Therefore what is needed is a fixture where parts can be easily and accurately loaded into an appropriate position for laser drilling and then held in the appropriate position without interfering with the laser drilling operation.
One embodiment of the present invention is directed to a fixture to align and hold a part for a machining operation. The fixture includes a base assembly and a locator assembly. The base assembly is configured to hold a part for a machining operation. The locator assembly has a first end pivotably connected to the base assembly and a second end opposite the first end. The second end of the locator assembly is pivotable between an engaged position adjacent the base assembly and a disengaged position opposite the base assembly. The locator assembly includes at least one part locator to align a part for a machining operation. The locator assembly is configured to position a part held in the base assembly against the at least one part locator to align a part in the base assembly for a machining operation in response to the second end of the locator assembly being in the engaged position.
Another embodiment of the present invention is directed to a fixture to align and hold a vane for a laser drilling operation. The fixture includes means for holding a vane for a laser drilling operation and a locator arm. The locator arm is connected to the means for holding a vane at one end and is detachably connected to the means for holding a vane at the other end. The locator arm is pivotable about the end connected to the means for holding a vane to move the other end to detachably connect to the means for holding a vane. The fixture also includes at least one locator. The at least one locator is disposed on one of the means for holding a vane and the locator arm. Finally, the means for holding a vane and the locator arm are configured to position a vane against the at least one locator in response to the second end of the locator arm being connected to the means for holding a vane such that a vane is in a predetermined alignment position for a laser drilling operation.
One advantage of the present invention is that it is easier for an operator to load a part into the fixture.
Another advantage of the present invention is that parts can be accurately loaded into the fixture in less time and with less effort.
Other features and advantages of the present invention will be apparent from the following more detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention.